/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package freemarker.template;

import java.util.Collection;

"collection" template language data type: a collection of values that can be enumerated, but can't be or not meant to be accessed by index or key, nor the number of elements in it is known. As such, this is very similar to Java's Iterable interface (but it predates that interface, hence the unfortunate class name). 
 Note that this is not a super-interface of TemplateSequenceModel, and implementations of that interface needn't also implement this interface just because they can. They should though, if enumeration with this interface is significantly faster than enumeration by index. The #list directive will enumerate using this interface if it's available. 
 The enumeration should be repeatable if that's possible with reasonable effort, otherwise a second enumeration attempt is allowed to throw an TemplateModelException. Generally, the interface user Java code need not handle that kind of exception, as in practice only the template author can handle it, by not listing such collections twice. 
 Note that to wrap Java's Collection, you should implement TemplateCollectionModelEx, not just this interface. /**
 * "collection" template language data type: a collection of values that can be enumerated, but can't be or not meant to
 * be accessed by index or key, nor the number of elements in it is known. As such, this is very similar to Java's
 * {@link Iterable} interface (but it predates that interface, hence the unfortunate class name).
 * 
 * <p>
 * Note that this is not a super-interface of {@link TemplateSequenceModel}, and implementations of that interface
 * needn't also implement this interface just because they can. They should though, if enumeration with this interface
 * is significantly faster than enumeration by index. The {@code #list} directive will enumerate using this interface if
 * it's available.
 * 
 * <p>
 * The enumeration should be repeatable if that's possible with reasonable effort, otherwise a second enumeration
 * attempt is allowed to throw an {@link TemplateModelException}. Generally, the interface user Java code need not
 * handle that kind of exception, as in practice only the template author can handle it, by not listing such collections
 * twice.
 * 
 * <p>
 * Note that to wrap Java's {@link Collection}, you should implement {@link TemplateCollectionModelEx}, not just this
 * interface.
 */
public interface TemplateCollectionModel extends TemplateModel {

    
Retrieves a template model iterator that is used to iterate over the elements in this collection.
/**
     * Retrieves a template model iterator that is used to iterate over the elements in this collection.
     */
    public TemplateModelIterator iterator() throws TemplateModelException;

}